In this story about medieval England, we find about how the legendary King Arthur became the king of England. It is a legend, not history.
King Uther is dying. He got sick and everyone knew he was going to die soon. When he went to his troops on the battlefield to encourage them, he got even sicker and went mute. Merlin the wizard comes to the castle, telling everyone that he will make the king speak so that he can tell them who his heir will be.
The king says that his son Arthur would be the heir and dies. Everyone is surprised because they didn't know the king had a son, but they decide to pray to God to reveal the heir of the kingdom.
While a knight is praying in the Church of Saint Paul, he sees, in the yard of the church, a sword driven through an anvil and a stone. He waits for the sermon to end and then finds written on the sword in golden letters:
Whoso pulleth out this sword of this stone and anvil, is rightwise king born of all England.
The Archbishop of Canterbury said that on Christmas, all the knights in the kingdom would have a tournament and then try to pull the sword out. That Christmas, a knight named Sir Ector, with his sons, Sir Kay and Arthur, were going towards the tournament, when Kay saw that his sword was not with him.
Arthur went back home to get it, but found the house locked, so he went to the sword in the stone and pulled it out, and rode back to his adopted father and brother.
When Kay saw the sword, he told his father about it, and the older knight was shocked. He asked Kay whether he took it out of the stone, but Kay said that Arthur gave it to him because he did not have a sword.
Then, the knights went back and put the sword back in the stone. When it was time for the knights of the kingdom to try to take it out, they all failed, except for Arthur. The other knights wanted a rematch, and they tried again on New Years, Easter, and Pentecost, and all the times Arthur was the only one who could take the sword out of the stone, so they made him king.